Epicyclic gearing



April 9, 1940. 1 THOMSON EPICYCLIC GEARING Filed Sept. 1, 1959 E. l. l

Il 7 IJ V IIA I /l/l Patented Apr. 9, 1940 UNITI-:D: STATES PATENT OFFICE Application Septemberl, 1939, Serial No. 293,0(l3 -In Great Britain September 1, 19381 j sciaims. (c1. uli-282) This invention has reference to an improvement in variable-'speed epicyclic gearing,`the object of the invention being the provision of mechanism which may be used to control the rotation of either of two rotatable shafts interconnected through theimproved gearing and which, when used in combination with a differential or balance gear, may be used to control the relative speeds of two shafts between which the differential or balance gear is interposed.

As will be hereinafter explained, the invention provides a means of steering endless track vehicles. The invention valso provides a means of minimising wheel spin in the driving wheels of motor road vehicles wherein the driving wheel axles are driven through a differential or balance gear.

According to the invention a variablespeed epicyclic gear comprises twin epicyclic gear trains interposed between two shafts and comprising a pair of sun wheels one fixed on eaclr shaft, two sets of planet wheels mounted on a carrier com mon to the two epicyclic gear trains, and an outer internally toothed ring rotatable upon each shaft, one set of planet wheels meshing withthe sun Wheel and outer ring on one shaft and the other set of planet `wheels meshing with the sun wheel and outer ringen the other shaft, and the "two outerr'rings are controlled by manually or'mechanically operable means for preventing rotation of the outer rings and for effecting or per mitting corresponding rotation in opposite directions of the two outer rings. Preferably the outer rings have external teeth which may conveniently mesh with a pinion or pinions rotatable on a fixed axis or on fixed axes, and rotationlof the pinion or pinions yin either direction can'be permitted or effected by hand-operated or mechanicallv-operated means. r

According to a modification. one outerrring is permanently fixed and the other outer ring is rotatable and controlled bv manually or mechanically operable means for effecting vor permitting its rotation in either direction,` for ex4 ample, the rotatable outer ring 'is 'externally' toothed and meshes with a pinion theyrotation of which in either direction can be permitted or eifected by hand-operated or mechanically-operated means.

A variable-speed epicvclic gear according to either of the two immediately preceding naragraphs may be usedin combination with a differential or balance gear for controlling the relative speeds of two shafts between which the differential or balance gear is interposed. In

such case the variable-speed epicyclic gear according to either of the two immediately preceding paragraphs is interposed between one of the Shafts and the differential or balance gear, onel of the sun wheels of the twin epicyclic gear trains being arranged to turn with the planet wheel carrier of the. differential or balance gear and the other sun wheel being fixed to the shaft which is disposed on the opposite side of the epicyclic gear to that of the planet wheel carrier of the differential or balance gear.

In order that the invention may be more clearly understood, reference is hereinafter made to the accompanying drawing wherein Fig. 1 is a sectional side view of the improved epicyclic gear and Fig. 2 is a front View of one half of the gearing. Fig. 3 is a sectional side View of the epicyclic gear combined with a differential or balance gear.

Referring firstly to Figs. 1 and 2, the drawing shows two coaxial rotatable shafts 5 and 6, their abutting ends turning freely in a carrier member 1. Either shaft may be a driving shaft. Shaft 5 has a sun wheel fixed thereon and shaft E has f a sun wheel 9 fixed thereon, the two sun whjeels being of the same diameter. Upon shaft 5 there is freely mounted a ring I havinginternal teeth. A similar ring II is freelymounted on shaft 6. Rotatable upon pins carried by the carrier mem# ber 'I are two sets of planet wheels' I2 and I3, all of equal size. The planet wheels I2 mesh with the sun wheel 8 and with the internal teeth trolled, er both rings may be rotated, or permitted to rotate, in opposite directions. In the form of the invention yshown Ain Figs. l and 2, the rings IIJ and I I have crown teeth which mesh with a common pinion I4 fixed on a control spindle I5. If the spindle i5 is prevented from rotation the rings I0 and II will remain stationary, and if the spindle I5 is rotated in either directionthe rings Ill and II will be rotatedin opposite directions, thus varying the relative speeds of the shafts 5 and E. Thus, if the shafts 5 and 6` drive the endless-track members of an endless-track vehicle, and if either shaft is driven froml the engine either directly or through Ia `differential gear, turningof the spindle I5 in either direction can be employed to vary the relative speeds of the shafts 5 and 6 and thus enable the vehicle to be steered in either direction. The spindle I5 can be controlled by a hand control or by any convenient mechanical means.

Referring now to Fig. 3, which shows my improved epicyclic gear combined with a differential or balance gear, like parts are given the same reference characters. In this case the shaft 5 forms the hollow hub of the sun wheel 8 for the passage through it of the shaft 5 which carries one bevel pinion I6 of a differential bevel gear interposed between the shaft 6 and a coaxial shaft I'I and supports a crown wheel I8 driven by a driving pinion I2. The crown wheel I8 is fixed to a rotatable casing or planet wheel carrier 2Q which, in known manner, carries the planet wheels 2I meshing with the bevel pinion I6 and with a bevel pinion 22 xed on shaft I1. The crown wheel I8 is fixed to the hollow hub 5 of the sun wheel The outer ring Iii is free to rotate on the said hub and the outer ring II is free to rotate on shaft S, their rotation being controlled by the pinion I4 on the control spindle l5. If the shafts 6 and il constitute the driif'ing axles of a road vehicle and the pinion I9 is driven from the engine, the gear will function as an ordinary balance gear so long as the control pinion I4 is free to rotate, because the outer rings I and I I and the planet wheels I2 and I3 will be free to revolve around the sun wheels 8 and 9. If either shaft E or il' overruns the other, the sun pinions 8 and 9 will cause relative rotation of the outer rings ES and i! so long as the con trol pinion I4 is free to permit such relative rotation. If, however, the rotation of the control pinion I 4 is controlled by retarding rotation of the control spindle I E, relative rotation of the outer rings IG and il can be controlled, with the result that the balancing action of the differential gear I5, IB, I9, 2t, SEI and 22 will be opposed and the relative speeds of the shafts and I will be controlled. By completely preventing rotation of the control spindle I 5 and its pinion It, the outer rings IB and II will be locked against rotation, thus putting the differential gear out of action, when the power transmitted by the driving pinion I9 to the axles G and I1 will be transmitted equally to both axles which will revolve at the same speed as each other. In this manner wheel slip of either of the wheels on the axles 6 and Il can be controlled.

I claim:

l. Variable-speed mechanism comprising, in combination, a. differential gear interposed between two shafts and including main sun wheels on each shaft, main planet wheels meshing with said main sun wheels, a rotatable carrier for said planet wheels, and means for rotating said carrier, twin epicyclic gear trains interposed between one of said shafts and the carrier, said gear trains including two secondary sun wheels, one on the last-mentioned shaft, and one turning with the carrier, two sets of secondary planet wheels each set meshing with' one of the secondary sun wheels, a secondary carrier for the two secondary sets of planet wheels, a pair of rotatable internally toothed elements meshing one with each set of secondary planet wheels, and controlling means for preventing rotation of both of said elements and for controlling rotation of said elements in opposite directions to one another.

2. Variable-speed mechanism comprising, in combination, a differential gear interposed between two shafts and including main sun wheels on each shaft, main planet wheels meshing with said main sun wheels, a rotatable carrier for said planet wheels, and means for rotating said carrier, twin epicyclic gear trains interposed between one of said shafts and the carrier, said gear trains including two secondary sun wheels, one on the last-mentioned shaft and one turning with the carrier, two sets of secondary planet wheels each set meshing with one of the secondary sun wheels, a secondary carrier for the two secondary sets of planet wheels, a pair of rotatable internally toothed elements meshing one with each set of secondary planet wheels, controlling means for preventing rotation of one of said elements and means for controlling rotation of the other of said elements in either direction and for preventing its rotation.

3. Variable-speed mechanism comprising, in combination, a differential gear interposed between two shafts and including main sun wheels on each shaft, mainplanet wheels meshing with said main sun wheels, a rotatable carrier for said planet Wheels, and means for rotating said carrier, twin epicyclic gear trains interposed between one of said shafts and the carrier, said gear trains including two secondary sun wheels, one on the last-mentioned shaft and one turning with the carrier, two sets of secondary planet wheels each set meshing with one of the secondary sun wheels, a secondary carrier for the two secondary sets of planet wheels, a pair of rotatable internally toothed elements meshing one with each set of secondary planet Wheels, controlling means for preventing rotation of one of said elements, a ring of external teeth on the other of said elements and a control pinion meshing with said ring.

4. Variable-speed mechanism comprising, in combination, a differential gear interposed between two shafts and including main sun wheels on each shaft, main planet wheels meshing with said main sun wheels, a rotatable carrier for said planet wheels, and means for rotating said carrier, twin epicyclic gear trains interposed between one of said shafts and the carrier, said gear trains including two secondary sun wheels, one on the last-mentioned shaft and one turning with the carrier, two sets of secondary planet Wheels each set meshing with one of the secondary sun wheels, a secondary carrier for the two secondary sets of planet wheels, a pair of rotatable internally toothed elements meshing one with each set of secondary planet wheels, a ring of external teeth on each of said elements and a control pinion meshing with each of said rings.

5. Variable-speed mechanism comprising, in combination, a differential gear interposed between two shafts and including main sun wheels on each shaft, main planet wheels meshing with said main sun wheels, a rotatable carrier for said planet wheels, and means for rotating said care rier, twin epicyclic gear trains interposed between one of said shafts and the carrier, said gear trains including two secondary sun wheels, one on the last-mentioned shaft and one turning with the carrier, two sets of secondary planet wheels each set meshing with one of the secondary sun wheels, a secondary carrier for the two secondary sets of planet wheels, a pair of rotatable internally toothed elements meshing one with each set of secondary planet wheels, a ring of external teeth on each of said elements and a common control pinion meshing with both of said rings.

JAMES THOMSON, 

